Solar cells convert light energy, such as that from sunlight, to electrical energy, and their production volume has increased considerably in recent years. Crystalline silicon solar cells, which are a type of solar cell, have an impurity diffusion layer, an anti-reflection layer and a light-incident side electrode on one of the surfaces (light incident side surface) of a crystalline silicon substrate, and a back surface electrode on the other surface. Electrical power generated by the crystalline solar cells can be taken to the outside by the light-incident side electrode and the back surface electrode.
Multiple electrically connected solar cells are referred to as a solar cell module. For example, in the case of a crystalline silicon solar cell module, in order to electrically connect a plurality of solar cells, wiring materials in the manner of interconnecting metal ribbons are soldered to electrodes formed on the surfaces of the solar cells, thereby forming electrical connections between adjacent solar cells.
Patent Document 1 and Patent Document 2 disclose devices for soldering tab leads to the top surface and back surface of solar cells as an example of technology used to connect a plurality of solar cells.
In addition, Patent Document 3 discloses a device for producing a string of solar cells by electrically connecting a plurality of solar cells. The device of Patent Document 3 is characterized by being provided with a connection stage that electrically connects corresponding solar cells, an electrical characteristics inspection unit that inspects the electrical characteristics of a string formed on the aforementioned connection stage, and a string placement unit that places the aforementioned string after classifying to one of a plurality of ranks corresponding to the inspected electrical characteristics.
Patent Document 4 discloses a wiring sheet for electrically connecting back contact solar cells in which a first conductivity-type electrode and a second conductivity-type electrode are arranged on one side of a semiconductor substrate. The wiring sheet of Patent Document 4 has an insulating substrate and a first wiring material provided on the insulating substrate, the first wiring material is provided with a plurality of cell arrangement units on which the back contact solar cells are arranged, and each of the cell arrangement units contains mutually electrically insulated first and second wires and has a second wiring material between the cell arrangement units electrically insulated from the first wire and the second wire.